Patent GB-727713-A (GB)
Title: Balanced hydraulic pump or motor of radial piston type
IPC: F01B1/06
Filed: 1953-09-17
Abstract: 727,713. Revolving cylinder pumps. YARMAK, J. Sept. 17, 1953 [Oct. 1, 1952], No. 25667/53. Class 102 (1). [Also in Group XXIX] In a revolving cylinder pump having a plurality of cylinders 12, Fig. 1, arranged in two rows in a block 11 rotationally mounted -on a fixed pintle 14, a roller bearinged guide drum 23 is transversely movable with respect to the pintle during each complete pump cycle, the drum centre 41, Fig. 2, moving from one side of the pintle centre 42 to the other side thereof to vary the quantity and direction of flow of liquid delivered through pintle bores 43, 44 and flexible pipes 45, 46 to opposite sides of a double-acting motor reciprocating, e.g. the shaker conveyer trough described in Specification 627,912, and the pistons 13 slidable in the cylinders are each provided with a concave end face on which a thrust roller 22 linked to the piston bears to provide an oscillating rolling support between the guide drum and the pistons to reduce frictional forces. Plates 30, 31 which carry the guide drum bearings 28, 29 form part of a rigid cradle urged by a spring 57 so that a cam-follower 56 constantly engages a cam 47 keyed to a shaft 48 driven through gearing 49 by the pump driving motor. To vary the eccentricity between the guide drum and the pintle and hence the stroke of the double-acting motor the cam 47, see Fig. 5, is formed along its length with cam surfaces of varying profile, the selected cam surface being positioned by a nut 61 and screwed spindle 58. Hydraulic thrusters 63 are provided to balance both the horizontal and vertical components of the hydraulic forces acting on the pistons 13. These thrusters comprise telescopic parts 67, 69. urged apart by a spring 72 and have knife-edged contact with bosses 75 on the rigid cradle and with fixed beams 76. Pressure liquid from the pintle bores 43, 44 is supplied to the thrusters through flexible pipes 77, 78, the upper thrusters communicating with the bore 43 and the lowerthrusters with the bore 44. When there is no eccentricity between the guide drum and the pintle, i.e. the centres 41, 42 are concentric the thrusters are in a neutral vertical position but in any other position they balance the hydraulic piston forces. Valve blocks 86, 89, Fig. 6, housing suction and relief valves 81, 83 are associated with the flexible pipes 77, 78 and the pintle bores 43, 44, so that a see-saw lever 93 carrying adjustable tappets 91, 92 operable through a spring-loaded spindle 96, and a weighted lever 97 by a cam 102 keyed to the shaft 48 unseats one or other of the suction valves 81 during the period when the double-acting motor is changing its direction of movement so that free escape of liquid may take place from its corresponding cylinder end to enable the piston to be adjusted towards its central position e.g., by springs. The pump casing is divided by a partition into chambers 110, 111, the level of the liquid in the chamber 110 in which the revolvable pump parts are housed being kept low so that they revolve substantially in air with a consequent reduction of frictional forces. Excess liquid in the chamber 110 is carried round by the pump parts and deposited on a deflector 116 whence it falls into the chamber 111 which carries the supply of liquid for the pump.